---
title: 20241003 - Use CSS Modules for Styling
---

## Status

- [ ] Proposed
- [x] Accepted
- [ ] Rejected
- [ ] Deprecated
- [ ] Superseded

## Context

Frontend styling approaches significantly impact development efficiency, maintainability, and performance. Our project required a styling solution that meets the following requirements:

1. **Design System Consistency** - Effective management of design tokens for a unified UI
2. **Implementation Efficiency** - Leveraging Figma style export to accelerate development
3. **AI Utilization** - Maximizing AI-assisted coding support
4. **Code Quality** - Preventing conflicts through scoped styling

We considered the following options to meet these requirements:

- CSS Modules
- Tailwind CSS
- CSS in JS

## Decision

We have decided to adopt CSS Modules as our styling approach. The key factors behind this decision are:

### 1. Stability and Future-Proofing with Standard Technologies

- **Standard CSS Specification** - Most stable styling approach using direct CSS
- **Immediate Access to New CSS Features** - Seamless utilization of features like CSS Variables
- **Tool Chain Compatibility** - Standard support in major bundlers (Webpack, Vite)
- **Technology Longevity** - Long-term viability independent of frameworks

### 2. Efficient Design System Implementation

- **Consistent Design Token Management** - Global variable management via CSS Variables
- **Direct Figma Integration** - Efficient conversion from design to CSS
- **Easy Theme Switching** - Simplified dark mode implementation through variable changes
- **Rapid Design Change Propagation** - Changes in one place affect the entire system

### 3. Team Development Optimization

- **Parallel Development via Component Isolation** - Independent work areas through scoping
- **Automatic Name Collision Avoidance** - Component-level CSS modularization
- **Minimal Learning Curve** - Development possible with standard CSS knowledge only
- **Code Review Simplification** - Improved readability through separation of styles and logic

### 4. High Compatibility with AI-Assisted Coding

- **High-Precision Generation Based on Standard Specifications** - Improved code generation accuracy
- **Abundant Reference Information** - Leveraging global information as learning data
- **Predictable Structure** - Streamlined debugging and modifications
- **Adaptation to Future AI Technology Evolution** - Continuous improvement expected for standard technologies

### 5. Balance Between Performance and Quality

- **Build-Time Optimization** - Reduced runtime overhead
- **Easy Code Splitting** - Component-level code splitting
- **Caching Strategy** - Efficient caching design
- **Bundle Size Optimization** - Automatic elimination of unnecessary styles

## Consequences

### Positive Impacts

1. **Design Quality and Consistency**

   - UI unification through design tokens
   - Visual coherence between components
   - Simplified multi-theme support

2. **Development Productivity**

   - Accelerated implementation from direct Figma export
   - Enhanced development efficiency through AI assistance
   - Parallel development at component level

3. **Code Quality**

   - Prevention of style conflicts through scoping
   - Clear responsibility separation at component level
   - Predictable style application

4. **Technical Stability**

   - Long-term maintainability through standard technologies
   - Tool chain compatibility
   - Performance optimization

### Negative Impacts

1. **UI Component Library**

   - Lack of compatibility with Tailwind CSS-based libraries (shadcn/ui, etc.)
   - Development and maintenance costs of custom UI component libraries
   - Additional effort for third-party integration

2. **Style Sharing and Global Management**

   - Complexity in designing shared styles between components
   - Need for special management of global styles
   - Construction of style override strategies

3. **Team Adaptation Costs**

   - CSS Modules convention adoption
   - Promoting understanding of the design token system
   - Maintaining consistent implementation style

### Technical Flexibility

1. **Possibility of Gradual Evolution**

   - Room for combining with other technologies in the future
   - Tolerance for different approaches in specific components
   - Natural adaptation to standard CSS evolution

2. **Development Environment Interoperability**

   - Integration with TypeScript
   - Standard integration with CI/CD environments
   - Compatibility with existing tool chains
